Slitter blade mounting assembly

ABSTRACT

A web slitter assembly of the type including a pair of rotating engaging slitter blades between which passes the web to be cut. The assembly includes a low friction blade mounting and special devices for accurately positioning the blades for cutting and loading the blades against each other. The accuracy of the positioning and loading is such that the blades can be driven solely by the web being cut without any external driving source.

United States Patent Frye et al. 14 Aug. 22, 1972 [54] SLITTER BLADE MOUNTING 3,540,340 11/1970 Koskela ..83/499 ASSEMBLY 246,892 9/1881 Marshall ..83/482 [72] Inventors: Kenneth G. Frye; Robert G; Lucas, g both of Downingtown Pas Soma M. arter Rohos St r F 2,897,893 8/1959 Rockstrom et a1. ..83/482 e 3,091,146 5/1963 Bulk ..83/482 x [73] Assignee: Beloit Corporation, Beloit, Wis. 3,332,326 7/1967 Haas ..83/482 X [22] Filed: Dec. 16, 1969 FOREIGN PATENTS OR APPLICATIONS [21] Appl. No.: 885,444 586,686 10/1933 Germany ..83/497 675,628 12/1963 Canada ..83/665 [52] US. Cl. ..83/482, 8834759072, 883515955 Primary Examiner prank T Yost 51 int. Cl. ..B26d 1/16, B26d 1 24 Momekmson Tayl and Hmds [58] Field of Search ..83/482, 497, 498, 502, 503, [57] ABSTRACT A web slitter assembly of the type including a pair of [56] References Cited rotating engaging slitter blades between which passes the web to be cut. The assembly includes a low fric- UNITED STATES PATENTS tion blade mounting and special devices for accurately positioning the blades for cutting and loading the 3 iig blades against each other. The accuracy of the posimgeln 83 6 5 tioning and loading is such that the blades can be Kocge 7 driven solely the web being cut without y exter 3,143,024 8/ 1964 Markowski ..83/497 a1 driving Source. 3,380,330 4/1968 Gilmore ..83/503 X 3,459,086 8/1969 Reeder, Jr. ..83/502 X 12 Claims, 5 Drawing Figures PATENTEDMJGZZ I912 3.685379 sum 1 [IF 3 INVENTORS KENNETH G. FRYE ROBERT G. LUCAS SHOMAY M. ROHOSY ATTORNEY SHEET 2 OF 3 INVENT KENNETH G. FRY

ROBERT G. LUCAS SHOMAY M. ROHOSY M tggi jawk ATTORNEY 1 SLI'ITER BLADE MOUNTING ASSEMBLY BACKGROUND OF THE INVENTION This invention relates to the lengthwise slitting of web material such as paper; and in particular, it relates to a new and improved web slitter assembly.

It is known to use a pair of rotating engaging discshaped blades to slit a web of material such as paper. The two discs touch and their circumferences overlap slightly, whereby the paper passing between the two discs in a plane generally perpendicular to a plane passing through the axes of rotation of the two discs is slit into a plurality of webs of smaller widths.

However, in some applications such as in the paper industry, these discs run at very high speed for 24 hours a day; and thus wear requirements are very demanding. Moreover, the task of forming a clean slit edge on the paper while running at high speed makes paper slitting a very delicate and precise operation.

Present slitters use external drive sources such as motors to rotate the disc-shaped blades to obtain the necessary rotational speeds. However, such motor driven slitters have suffered from certain disadvantages including, inter alia, excessive wear. For example, during certain periods the cutting load might be very light or it may be eliminated altogether such as when paper is not passing through the slitter assembly. However, the motors would continue to run during these periods, thus continuing to rotate the discs which then rub against each other with an excessive force causing excessive wear. On the other hand, precise and instantaneous control of the motor speeds might render the assembly uneconomical. It would not be feasible to eliminate the above disadvantages by simply removing the motor altogether because under previous conditions the slitters may not rotate at all and in any event there would be no means for controlling the loading force and the relative positions of the blades.

Thus, there exists a need for a new and improved slitter assembly which overcomes disadvantages of slitter assemblies known heretofore.

SUMMARY OF THE INVENTION Thus, it is a purpose of the present invention to provide a new and improved slitter assembly of the type for lengthwise slitting of a web of material.

This purpose of the present invention is achieved by providing a slitter assembly having new and improved slitter blade mounting and loading means which permit the slitter blades to be driven solely by the web being cut, without any need for external driving sources. Consequently, with this arrangement the speed of rotation of the blade is directly responsive through actual contact to the speed of movement of the web being cut.

In the assembly of the present invention, both the upper and lower slitter blades are mounted for movement along a rail (commonly referred to as a dovetail) to any transverse position across the winding apparatus on which the slitter assembly is mounted. A pinion gear on each of the upper and lower slitter blade assemblies engages a rack fixed to its respective dovetail to provide transverse movement. Further, each of the slitter assemblies includes a fluid operated clamping device for clamping the respective slitter assembly to the respective dovetail rail at the selected crosswise, or transverse position. Moreover, in both the upper and 2 lower slitter assemblies, the respective blades are mounted on low friction roller bearings which permit free rotation of the blades relative to the assemblies on which each is mounted.

In addition to the above, the upper slitter claim 1 assembly includes means for moving piston-and-cylinder upper slitter blade vertically from a raised inoperative position to a lowered operative position. Further means are provided for moving the upper slitter blade along its own axis for loading the upper slitter blade against the lower slitter blade. This side loading means is constructed such that it does not interfere with the low friction properties of the bearings on which the upper slitter blade is mounted. In addition, this side loading means is variable so that the loading force of the upper blade against the lower blade can be varied in accordance with operating conditions. The upper slitter blade assembly also includes means for toeing-in the upper slitter blade relative to the lower slitter blade.

The various features outlined above combine with each other to precisely and accurately control loading and positioning of the blades relative to each other such that the blades will be driven at the proper speed by the web itself without external motor means thereby positively correlating and hence controlling the speed of movement of the blades relative to the speed of movement of the web being cut. Thus, in a surprisingly simplified manner, the present invention overcomes numerous disadvantages of the prior art including speed control of the blades and the elimination of excess blade wear.

Thus, it is a purpose of the invention to provide a new and improved slitter blade assembly for lengthwise slitting of web material such as paper or the like.

It is another object of the invention to provide a new and improved slitter blade assembly which may be driven solely by the web of material being cut.

It is another object of this invention to provide a new and improved slitter blade assembly including improved means for moving one of the slitter blades between an inoperative position and an operative position, properly loaded against the other blade.

It is another object of this invention to provide a new and improved means for more accurately positioning the slitter blade assembly on the dovetail rail.

It is another object of this invention to provide a slitter blade assembly having improved slitter blade positioning means coupled with low friction mounting means such that the blades can be driven at speeds related directly to the speed of movement of the web being cut.

Other objects and the attendant advantages of the present invention will become apparent from the detailed description to follow, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS There follows a detailed description of the invention to be read together with the accompanying drawings, the description and the drawings being provided only to illustrate a preferred embodiment of the invention.

FIG. 1 is a side elevational view of the slitting station DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, like elements represent like numerals throughout the several views.

FIG. 1 illustrates the slitting station of a web rewinding apparatus. Such a re-winding apparatus is used, for example, to wind rolls of newly formed paper into rolls of smaller diameter and also, and more importantly, for the purposes of the present invention, to slit a web of paper into a plurality of rolls having a smaller width. In FIG. 1 the web 17 is supported for movement through the slitting station 10 by means of rollers 18. These rollers form the subject matter of a separate patent application of common ownership with the present invention and filed concurrently herewith.

The slitter assembly of the present invention includes an upper slitter assembly 11 and a lower slitter assembly 14. The upper assembly 11 is movable across the machine (perpendicular to the plane of the paper) along a dovetail-shaped rail 13. A slitter blade 12 which may have an 8-inch diameter is mounted on the assembly 11. The lower slitter assembly 14 is also movable across the machine on the dovetail-shaped rail 16 and includes a slitter blade mounted thereon. In cooperation with an 8-inch upper slitter blade it is preferable to use an 8.5 inch diameter lower blade.

The upper slitter blade assembly 11 is shown in greater detail in FIGS. 2 and 3. A slitter frame has formed integrally therewith a clamp portion 26, a vertically extending portion 27, an upper portion 28 and a down-stop 29. The dovetail-shaped rail 13 includes an upper portion 13T and a lower portion 13B which cooperate with the portions 28 and 26, respectively, of the slitter frame 25. Movement of the slitter frame along the rail 13 is provided by engagement between a pinion 52 of the slitter frame 25 and a rack 30 fixed on and extending longitudinally with the rail 13.

A first slitter arm is movable vertically with respect to frame 25 about the axis of pivot pin (see in particular FIG. 3). The arm 35 includes an upwardly extending abutment 36 and a split hub portion 37. A clamp 38 threadedly engages the two portions of the split hub 37 for urging the two portions of the hub together. A second slitter arm 41, similar to the arm 35 except that it does not have a split hub, is located on the opposite side of the slitter blade 12 (see FIG; 3).

For moving the entire upper slitter assembly 1 1 along the rail 13, the slitter frame 25 includes a hand-wheel integral with a pin 51 which extends through portion 28 and drivingly engages the pinion 52. Thus, by turning handwheel 50, the pinion 52 is turned and moved along rack 30 whereby the entire upper slitter assembly 1 1 is moved along the rail 13.

The sub-assembly including the slitter blade 12 and the two arms 35 and 41 are moved vertically about pivot pin 40 by means of a vertical movement cylinder 57. By introducing fluid to the chamber to the right of piston diaphragm 58 (see FIG. 2) the piston 58 is moved to the left and this in turn acts through pivot pin 59, link 60, pivot pin 61 and abutment 36 to move the said subassembly downwardly, that is clockwise about pivot pin 40 as shown in FIG. 2. Downward movement of this sub-assembly is limited by engagement of the stop member 39 on the arm 35 with a stop member 29.

on the frame 25. A spring 50 may be provided adjacentv these two stop members and tending to urge the arm 25, and thus the said sub-assembly upwardly, that is clockwise relative to pivot pin 40. Thus, pressurizing cylinder 57 will cause downward movement of the slitter blade 12 and the release of pressure from this cylinder will permit the said spring to move the sub-assembly and hence the slitter blade 12 upwardly until the piston 58 engages the end wall of cylinder 57.

In operation, the lower slitter blade will be positioned first. The upper slitter blade will then be moved transversely of the machine to the proper position. The blade will first be lowered in the manner as described above. Next, the blade will be moved parallel to its axis to properly load the upper blade against the lower blade. The low friction support for the slitter blade and the means for exerting this sideward force against the slitter blade are shown in FIG. 3. Slitter blade 12 in non-rotationally connected to a sleeve 65 through a radially extending pin 64. The blade 12 is fixed axially on the sleeve 65 by means of a holding nut 66, the inside of which threadedly engages the exterior surface of sleeve 65. Within sleeve 65 is a low friction roller bearing 67, the interior of which supports a non-rotating shaft 68. The bearing space may be provided with suitable seals of a suitable material such as teflon.

A feature of the invention is that the side loading thrust on the blade 12 is parallel to the axis of the blade 12 and parallel to the axis of bearing 67 and shaft 68. Consequently, this side loading force does not interfere with the function of the bearing. Thus, the bearing continues to act as a low friction bearing permitting free rotation of the loaded blade 12 relative to the shaft 68.

The sideward thrust of blade 12 is provided by introducing fluid under pressure through a line 74 to a chamber 71 where the pressurized fluid acts against a rolling diaphragm 72 and the righthand end of shaft 68 thereby moving the entire bearing assembly and the blade 12 to the left (as shown in FIG. 3) to load the blade 12 against the lower blade 15. The shaft 68 is returned to the right by introducing pressurized fluid through a line (not shown) to the space 78 whereat the fluid acts on the lefthand end of shaft 68. In a preferred embodiment, this stroke may be 0.22 inches.

FIG. 3 also illustrates the means for mounting and dismounting a blade to and from the sub-assembly. First the clamp 38 is loosened permitting rightward movement of firstshaft mounting along cylindrical surface 73. The entire sub-assembly may be moved to the right until the lefthand end of shaft 68 is spaced from the second shaft mounting 75. The holding nut 66 is then removed and the slitter blade 12 removed from the sleeve 65 to the left (as shown in FIG. 3). A new blade may then be mounted, the holding nut 66 returned to the sleeve 65 and the lefthand end of shaft 68 re-introduced into the second shaft mounting 75. To further facilitate this operation, the generally cylindrical mounting 75 is pivotally connected at pivot pin 76 through a bushing 77 to the second arm 41. Thus, after the shaft 68 has been removed from portion 75, the

portion 75 can be turned about the axis of pivot pin 76 into or out of the paper to permit free access to the nut 66.

FIG. 3 illustrates the means for turning the entire sub-assembly including arms 35 and 41 angularly about a vertical axis to provide toe-in of the upper blade 12 relative to the lower blade 15. A pair of inclined cam surfaces 85 fixed to the frame 25 about the pivot pin 40 are engaged by pins 87 which are movable along a curvedslot 88. The pins 87 are in turn connected to flat plates 86 which are in turn connected to the sub-assembly including arms 35 and 41 at pivot pins 89. For clarity, it should be noted that these plate 86 are not connected to the pivot pin 40. Thus, by turning the plates 86 about the axis of pins 89, the location of pins 87 will vary along the surface of cam plates 85. The height of these cam plates will vary along the said path so that the arms 35 and 41 will be moved about a vertical axis depending upon the position of pins 87 relative to cam plates 85. In a preferred embodiment, the plates 86 may be permitted to move through approximately 90 about axis pins 89 and this will provide a turning movement of the sub-assembly including arms 35 and 41 through a range of between and l.5. For balanced control, the two cams 85 should be mounted symmetrically so that the said turning movement is accomplished by turning the two plates 86 by an equal amount in opposite directions.

Referring again to FIG. 2, the sub-assembly is fixed at a selected position along rail 13 by first reaching the selected position along rack 30 and then introducing pressure to the chamber 53 thereby moving the piston 54 upwardly against portion 13B so that the portions 13T and 13B will be firmly engaged by portions 28 and piston 54, respectively.

FIGS. 4 and illustrate the lower slitter blade assembly 14. This assembly includes a lower slitter arm 95 having formed integrally therewith a back portion 96, a top portion 97, all of which portions are pivotally connected to a lower clamp portion 99 through a pivot pin 98. This lower clamp portion includes a flange 100 having an adjusting bolt 101 and a tightening nut 102 engaged therewith. This portion 99 includes a fluid operated clamp 103 for clamping this lower slitter assembly to the dovetail 16. A piston 105 in a cylinder 104 is urged upwardly against the lower portion 16B of the dovetail 16, also urging the portion 97 against dovetail portion 16T. A return spring 106 urges the piston 105 downwardly so that the clamp is disengaged when fluid is released from the cylinder 104. This lower slitter assembly may also be clamped to the dovetail 16 mechanically by turning the bolt 101 with its lower end engaging the arm 95 thereby turning the portion 99 about pivot pin 98 such that an extension 117 of the cylinder 104 will mechanically engage the dovetail portion 16B. Movement of the lower slitter assembly along the dovetail 16 is provided by turning a hand wheel 115, and thereby turning a pinion 116 to move the assembly along rack 16R.

FIG. 5 illustrates the mounting assembly for the lower slitter blade 15, which mounting assembly is also characterized by low friction free rolling like the upper slitter blade mounting assembly. This assembly includes a pin 107, a holding nut 108, a sleeve 109 and bearing 110, which elements correspond, respectively,

with the elements 64, 66, 65 and 67, as shown for the upper slitter blade assembly in FIG. 3. This lower slitter blade assembly also includes a hub 112 which receives the end of a non-rotating shaft 111. The righthand end of this shaft includes a pivot connection 113 to a locking handle 114. This handle may be moved upwardly, that is counterclockwise as shown in FIG. 5, against the holding nut 108. Alternatively, it can be moved downwardly such that it extends along the axis of shaft 111 so that the holding nut 108 and the blade 15 can be removed from the assembly to the right as shown in FIG. 5.

There has thus been described a combination of ele' ments which cooperate and interrelate with each other to provide a substantially improved slitter mounting assembly. The combination of at least some of the following factors permit controlled operation with the motive force for the blades provided entirely by the moving web; low friction roller bearings, controlled toeing-in, controlled blade loading, proper penetration of the blades across the plane of the paper (penetration is also defined as the vertical overlap of the two blades). Further, accurate control is provided by permitting variation of the side loading force. For example, under high speed conditions high pressure and hence a high loading force is required. Alternatively, during low speeds a low pressure, and hence a low loading force is required. If these conditions are not met, for example if high loading is provided during low speed operation, the result could be considerable excess wear of the blades. Moreover, proper penetration is extremely important for determining the characteristics of the cutting operation. The fluid operated device now permits good control of the lowering of the upper blade, and hence of penetration. All elements of both assemblies, including the clamping devices, are arranged such that they do not bind the bearings or otherwise produce torque drag on the sleeves of the blade mounting assemblies since these sleeves rotate with the blade. Fluid operated clamping of the assembly to the dovetail-shaped rail permits such clamping without twisting of the assembly which would be inherent with a mechanical screw. Lowering of the sub-assembly including arms 35 and 41 may be carefully controlled by employing an orifice in the fluid line to the chamber 57.

Another feature of the invention is that both the upper and lower slitter blade mountings are somewhat flexible at their sleeves so that each slitter assembly can give in the axial direction when momentarily acted on by the other slitter blade. This is in contrast to some previous arrangement wherein at least one of the blades had very little if any flexibility.

Although the invention has been described in considerable detail with respect to a preferred embodiment thereof, it will be apparent that the invention is capable of numerous modifications and variations apparent to those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1. A web slitting apparatus comprising, upper and lower disc-shaped cutter blades mounted, respectively, on upper and lower slitter blade assemblies such that the blades are rotatable about generally parallel axes for slitting lengthwise a web passing between the blades, an elongated rail, at least one of said assemblies including;

a frame mounted on and moveable along the rail to vary the position of the assembly along the rail, a pair of arms pivotally connected to the frame for movement about a pivot axis generally parallel to the blade axes, said arms extending outwardly from said pivot axis and being generally horizontal when the blades engage, a bearing assembly connecting these arms together at their outer ends, the said one blade being mounted on said bearing assembly between said arms,

means interconnecting the frame and the arms to move the axis of the said one blade towards and away from the axis of the other blade and including means for turning said arms about an axis generally perpendicular to the said pivot axis to toe-in the said one slitter blade relative to the other slitter blade.

2. A web slitting apparatus according to claim 1 including a stop means for limiting movement of the arm and the said one blade towards the other blade under the action of said fluid operated piston-and-cylinder unit, and a spring mounted between the frame and the arm to urge the arm and the said one blade away from the other blade.

3. A web slitting apparatus according to claim including a further fluid operated piston-cylinder unit located in one of the said arms for moving the blade parallel to its axis towards and away from the other blade.

4. A web slitting apparatus according to claim 3, in which the said further piston-and-cylinder unit acts directly on the bearing assembly of the said one blade.

5. A web slitting apparatus according to claim 1, wherein the last said means includes a pair of inclined cams mounted on opposite sides of the slitter assembly, and follower means mounted one on each arm and engaging said cams and movable thereover to cause said turning movement.

6. A web slitting apparatus according to claim 1, wherein the outer end of one of said arms is turnable about an axis through that arm relative to the remainder of that arm whereby said end is movable out of the axis of the said one blade.

7. A web slitting apparatus according to claim 6, including a nut holding the blade on the bearing assembly, said nut being positioned on the side of the blade towards the said one arm having the movable outer end, the said nut being removable from the bearing assembly in an axial direction, whereby when the said outer end of the said one arm is turned about the said axis and the said nut is moved axially, the said one blade can be removed axially from the bearing assembly.

8. A web slitting apparatus according to claim 1, including a connecting means for interconnecting said arms, and wherein the means interconnecting the frame and the arms comprises a piston connected to the connecting means and a cylinder cooperating with the piston and connected to the frame.

9. A web slitter assembly comprising a pair of discshaped slitter blades rotatable about generally parallel axes and arranged to move into engagement with each other to slit lengthwise a web passing between the blades in a plane generally parallel to the axes of the 65 blades, said assembly including an upper slitter blade assembly and a lower slitter blade assembly, each of said assemblies being mounted on a rail for movement therealong, whereby the position of the slitter blades on the respective rails can be varied, and wherein at least one of said slitter blade assemblies includes a fluid operated means for clamping that slitter blade assembly against its respective rail.

10. A web slitter assembly comprising a pair of discshaped slitter blades rotatable about generally parallel axes and arranged to move into engagement with each other to slit lengthwise a web passing between the blades in a plane generally parallel to the axes of the blades, said assembly including an an upper slitter blade assembly and a lower slitter blade assembly, at least one of said assemblies including a means for turning that assembly and hence'also turning the blade about an axis generally perpendicular to the plane of the web being cut to toe-in that slitter blade relative to the slitter blade of the other assembly, the last said means including a pair of inclined cams mounted on opposite sides of the said one assembly, and follower means engaging said cams and movable thereover to cause said turning movement.

11. A web slitting apparatus comprising, upper and lower disc-shaped cutter blades mounted, respectively, on upper and lower slitter blade assemblies such that the blades are rotatable about generally parallel axes for slitting lengthwise a web passing between the blades, an elongated rail, at least one of said assemblies including;

a frame mounted on and movable along the rail to vary the position of the assembly along the rail, a pair of arms pivotally connected to the frame for movement about a pivot axis generally parallel to the blades axes, said arms extending outwardly from said pivot axis and being generally horizontal when the blades engage, a bearing assembly connecting these arms together at their outer ends, the said one blade being mounted on said bearing assembly between said arms,

means interconnecting the frame and the arms to move the axis of the said one blade towards and away from the axis of the other blade,

and including a further fluid operated piston and cylinder unit located in one of the said arms for moving the blade parallel to its axis towards and away from the other blade.

12. A web slitting apparatus comprising, upper and lower disc-shaped cutter blades mounted, respectively, on upper and lower slitter blade assemblies such that the blades are rotatable about generally parallel axes for slitting lengthwise a web passing between the blades, an elongated rail, at least one of said assemblies including:

a frame mounted on and movable along the rail to vary the position of the assembly along the rail, a pair of arms pivotally connected to the frame for movement about a pivot axis generally parallel to the blades axes, said arms extending outwardly from said pivot axis and being generally horizontal when the blades engage, a bearing assembly connecting these arms together at their outer ends, the said one blade being mounted on said bearing assembly between said arms,

means interconnecting the frame and the arms to move the axis of the said one blade towards and away from the axis of the other blade,

and wherein the outer end of one of said arms is tumable about an axis through that arm relative to the remainder of that arm whereby said end is movable out of the axis of the said one blade. 

1. A web slitting apparatus comprising, upper and lower discshaped cutter blades mounted, respectively, on upper and lower slitter blade assemblies such that the blades are rotatable about generally parallel axes for slitting lengthwise a web passing between the blades, an elongated rail, at least one of said assemblies including; a frame mounted on and movable along the rail to vary the position of the assembly along the rail, a pair of arms, pivotally connected to the frame for movement about a pivot axis generally parallel to the blade axes, said arms extending outwardly from said pivot axis and being generally horizontal when the blades engage, a bearing assembly connecting these arms together at their outer ends, the said one blade being mounted on said bearing assembly between said arms, means interconnecting the frame and the arms to move the axis of the said one blade towards and away from the axis of the other blade and including means for turning said arms about an axis generally perpendicular to the said pivot axis to toe-in the said one slitter blade relative to the other slitter blade.
 2. A web slitting apparatus according to claim 1 including a stop means for limiting movement of the arm and the said one blade towards the other blade under the action of said fluid operated piston-and-cylinder unit, and a spring mounted between the frame and the arm to urge the arm and the said one blade away from the other blade.
 3. A web slitting apparatus according to claim 1 including a further fluid operated piston-and-cylinder unit located in one of the said arms for moving the blade parallel to its axis towards and away from the other blade.
 4. A web slitting apparatus according to claim 3, in which the said further piston-and-cylinder unit acts directly on the bearing assembly of the said one blade.
 5. A web slitting apparatus according to claim 1, wherein the last said means includes a pair of inclined cams mounted on opposite sides of the slitter assembly, and follower means mounted one on each arm and engaging said cams and movable thereover to cause said turning movement.
 6. A web slitting apparatus according to claim 1, wherein the outer end of one of said arms is turnable about an axis through that arm relative to the remainder of that arm whereby said end is movable out of the axis of the said one blade.
 7. A web slitting apparatus according to claim 6, including a nut holding the blade on the bearing assembly, said nut being positioned On the side of the blade towards the said one arm having the movable outer end, the said nut being removable from the bearing assembly in an axial direction, whereby when the said outer end of the said one arm is turned about the said axis and the said nut is moved axially, the said one blade can be removed axially from the bearing assembly.
 8. A web slitting apparatus according to claim 1, including a connecting means for interconnecting said arms, and wherein the means interconnecting the frame and the arms comprises a piston connected to the connecting means and a cylinder cooperating with the piston and connected to the frame.
 9. A web slitter assembly comprising a pair of disc-shaped slitter blades rotatable about generally parallel axes and arranged to move into engagement with each other to slit lengthwise a web passing between the blades in a plane generally parallel to the axes of the blades, said assembly including an upper slitter blade assembly and a lower slitter blade assembly, each of said assemblies being mounted on a rail for movement therealong, whereby the position of the slitter blades on the respective rails can be varied, and wherein at least one of said slitter blade assemblies includes a fluid operated means for clamping that slitter blade assembly against its respective rail.
 10. A web slitter assembly comprising a pair of disc-shaped slitter blades rotatable about generally parallel axes and arranged to move into engagement with each other to slit lengthwise a web passing between the blades in a plane generally parallel to the axes of the blades, said assembly including an an upper slitter blade assembly and a lower slitter blade assembly, at least one of said assemblies including a means for turning that assembly and hence also turning the blade about an axis generally perpendicular to the plane of the web being cut to toe-in that slitter blade relative to the slitter blade of the other assembly, the last said means including a pair of inclined cams mounted on opposite sides of the said one assembly, and follower means engaging said cams and movable thereover to cause said turning movement.
 11. A web slitting apparatus comprising, upper and lower disc-shaped cutter blades mounted, respectively, on upper and lower slitter blade assemblies such that the blades are rotatable about generally parallel axes for slitting lengthwise a web passing between the blades, an elongated rail, at least one of said assemblies including; a frame mounted on and movable along the rail to vary the position of the assembly along the rail, a pair of arms pivotally connected to the frame for movement about a pivot axis generally parallel to the blades axes, said arms extending outwardly from said pivot axis and being generally horizontal when the blades engage, a bearing assembly connecting these arms together at their outer ends, the said one blade being mounted on said bearing assembly between said arms, means interconnecting the frame and the arms to move the axis of the said one blade towards and away from the axis of the other blade, and including a further fluid operated piston and cylinder unit located in one of the said arms for moving the blade parallel to its axis towards and away from the other blade.
 12. A web slitting apparatus comprising, upper and lower disc-shaped cutter blades mounted, respectively, on upper and lower slitter blade assemblies such that the blades are rotatable about generally parallel axes for slitting lengthwise a web passing between the blades, an elongated rail, at least one of said assemblies including: a frame mounted on and movable along the rail to vary the position of the assembly along the rail, a pair of arms pivotally connected to the frame for movement about a pivot axis generally parallel to the blades axes, said arms extending outwardly from said pivot axis and being generally horizontal when the blades engage, a bearing assembly connecting these arms together at their outer ends, the said oNe blade being mounted on said bearing assembly between said arms, means interconnecting the frame and the arms to move the axis of the said one blade towards and away from the axis of the other blade, and wherein the outer end of one of said arms is turnable about an axis through that arm relative to the remainder of that arm whereby said end is movable out of the axis of the said one blade. 